1. Field of the Invention
The present invention relates to a novel protease which specifically cleaves the peptide bond at the carboxyl termini of glutamic acid residues in the amino acid sequences of polypeptides, a method for producing the protease from bacteria of the genus Bacillus, a DNA sequence encoding the protease, an expression vector containing the DNA sequence, a transformant obtained by introducing this expression vector into a host, and a method for producing the protease using the transformant.
2. Description of the Prior Art
The V8 protease derived from the V8 strain of Staphylococcus aureus is already known as an enzyme which acts upon proteins (i.e., polypeptides) and specifically cleaves the peptide bond at the carboxyl terminal of glutamic acid (Glu) residues (Gabriel R. Drapeau et al., J. Biol. Chem. 247, 20, 6720-6726, 1972). This enzyme is classified as a serine protease. C. Carmona et al. have cloned the DNA sequence encoding this enzyme (Nucl. Acids Res., 15, 6757, 1987).
A similar enzyme, an endopetidase which is specific for acidic amino acid residue and is derived from an actinomycete bacterium Streptomyces griseus, is also known (Norio Yoshida et al., J. Biochem. 104, 3, 451-456, 1988). Furthermore, an endoprotease which is specific for glutamic acid residue derived from Bacillus subtilis is also known (Takuro Niidome, Norio Yoshida, Fusahiro Ogata, Akio Ito, and Kosaku Noda, J. Biochem. 108, 965-970, 1990); Abstracts of 62nd General Conference of the Japan Biochemical Society).
The aforesaid enzymes are useful when specific cleavage of proteins at the aforesaid sites is desired for the purposes of protein structural analysis, etc., or when recombinant DNA techniques have been employed to produce a desired protein in the form of a certain fusion protein, from which the desired protein is to be obtained by cleavage. In the latter case, for example, when the desired protein has been produced in the form of a fusion protein in which the desired protein is linked with another protein via a glutamic acid residue, the desired protein can be separated by cleavage with such an enzyme. For these reasons, the availability of other proteases possessing this type of enzymatic activity, in addition to those mentioned above, would be highly desirable.